Conferencing is the capability in a communications system of coupling information signals among three or more system subscribers. The information signals are typically voice signals but, with the advent of multimedia communications capabilities, can also be non-voice signals, i.e., data, video, facsimile and the like.
Echoes are a major problem in conferencing circuits. When a large number of circuits are interconnected in a conference call, the cumulative effect of many echo paths severely degrades voice quality and circuit instability can render the communications unintelligible. Prior art solutions to the problem of echoes have either introduced attenuation into each of the circuits or have provided echo cancellation via circuitry disposed in each of the circuits interconnected in the conference call. The former technique limits the maximum number of system users or "conferees" in a conference call while the latter solution to the echo problem is expensive to implement in communications systems. It Would, therefore, be desirable if a readily implementable, low-cost echo reduction technique could be provided for conferencing circuitry.